Interpretive Summary: For many domesticated crops, germplasm from wild relatives has provided a source of genes for crop improvement leading to disease resistance and tolerance for biotic stresses such as drought and salinity. To ensure that the sunflower collection in the National Plant Germplasm System (NPGS) contains the maximum possible genetic diversity, we are actively working to collect from populations representing the full geographic range of all 66 Helianthus taxa. Helianthus is native to North America and only one taxon, the showy sunflower, does not have populations in the United States. Domestic collection trips are less complex than international explorations to arrange. This research describes three trips taken in the United States during 2005 to collect targeted wild sunflower species for the NPGS. Populations of targeted species were identified by interviewing local botanists and by locating the collection sites of specimens documented in area herbaria. Several sites were chance discoveries in regions of appropriate habitat. We took digital images at each collection site and pressed voucher specimens, which were deposited in the USDA-ARS wild Helianthus herbarium in Fargo, ND. Nine accessions of Cusick’s sunflower were collected during the June trip in Washington and Oregon. Nine accessions of Cusick’s sunflower and six accessions of desert sunflower were collected during the June California and Nevada trip. Forty-five accessions of little sunflower, one accession of Nuttall’s sunflower and one accession of wild annual sunflower were collected during the August Colorado and Wyoming trip. The NPGS sunflower germplasm collection is maintained and distributed at the North Central Regional Plant Introduction Station in Ames, IA. The addition of these wild species populations to the sunflower germplasm collection will ensure that they will be available for future improvement of cultivated sunflower.

Technical Abstract:
For many domesticated crops, germplasm from wild relatives has provided a source of genes for crop improvement leading to disease resistance and tolerance for biotic stresses such as drought and salinity. To ensure that the sunflower collection in the National Plant Germplasm System (NPGS) contains the maximum possible genetic diversity, we are actively working to collect from populations representing the full geographic range of all 66 Helianthus taxa. Helianthus is native to North America and only one taxon, Helianthus niveus ssp. niveus, does not have populations in the United States. Domestic collection trips are less complex than international explorations to arrange. This research describes three trips taken in the United States during 2005 to collect targeted wild Helianthus species for the NPGS. Populations of targeted species were identified by interviewing local botanists and by locating the collection sites of specimens documented in area herbaria. Several sites were chance discoveries in regions of appropriate habitat. We took digital images at each collection site and pressed voucher specimens, which were deposited in the USDA-ARS wild Helianthus herbarium in Fargo, ND. Nine accessions of H. cusickii were collected during the June trip in Washington and Oregon. Nine accessions of H. cusickii and six accessions of H. deserticola were collected during the June California and Nevada trip. Forty-five accessions of H. pumilus, one accession of H. nuttallii and one accession of H. annuus were collected during the August Colorado and Wyoming trip. The NPGS sunflower germplasm collection is maintained and distributed at the North Central Regional Plant Introduction Station in Ames, IA. The addition of these wild species populations to the sunflower germplasm collection will ensure that they will be available for future improvement of cultivated sunflower.